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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*****************************************************************************
* Copyright (C) 1996-2014, International Business Machines Corporation and others.
* All Rights Reserved.
*****************************************************************************
*
* File sortkey.h
*
* Created by: Helena Shih
*
* Modification History:
*
* Date Name Description
*
* 6/20/97 helena Java class name change.
* 8/18/97 helena Added internal API documentation.
* 6/26/98 erm Changed to use byte arrays and memcmp.
*****************************************************************************
*/
#ifndef SORTKEY_H
#define SORTKEY_H
#include "unicode/utypes.h"
#if U_SHOW_CPLUSPLUS_API
/**
* \file
* \brief C++ API: Keys for comparing strings multiple times.
*/
#if !UCONFIG_NO_COLLATION
#include "unicode/uobject.h"
#include "unicode/unistr.h"
#include "unicode/coll.h"
U_NAMESPACE_BEGIN
/* forward declaration */
class RuleBasedCollator;
class CollationKeyByteSink;
/**
*
* Collation keys are generated by the Collator class. Use the CollationKey objects
* instead of Collator to compare strings multiple times. A CollationKey
* preprocesses the comparison information from the Collator object to
* make the comparison faster. If you are not going to comparing strings
* multiple times, then using the Collator object is generally faster,
* since it only processes as much of the string as needed to make a
* comparison.
* <p> For example (with strength == tertiary)
* <p>When comparing "Abernathy" to "Baggins-Smythworthy", Collator
* only needs to process a couple of characters, while a comparison
* with CollationKeys will process all of the characters. On the other hand,
* if you are doing a sort of a number of fields, it is much faster to use
* CollationKeys, since you will be comparing strings multiple times.
* <p>Typical use of CollationKeys are in databases, where you store a CollationKey
* in a hidden field, and use it for sorting or indexing.
*
* <p>Example of use:
* <pre>
* \code
* UErrorCode success = U_ZERO_ERROR;
* Collator* myCollator = Collator::createInstance(success);
* CollationKey* keys = new CollationKey [3];
* myCollator->getCollationKey("Tom", keys[0], success );
* myCollator->getCollationKey("Dick", keys[1], success );
* myCollator->getCollationKey("Harry", keys[2], success );
*
* // Inside body of sort routine, compare keys this way:
* CollationKey tmp;
* if(keys[0].compareTo( keys[1] ) > 0 ) {
* tmp = keys[0]; keys[0] = keys[1]; keys[1] = tmp;
* }
* //...
* \endcode
* </pre>
* <p>Because Collator::compare()'s algorithm is complex, it is faster to sort
* long lists of words by retrieving collation keys with Collator::getCollationKey().
* You can then cache the collation keys and compare them using CollationKey::compareTo().
* <p>
* <strong>Note:</strong> <code>Collator</code>s with different Locale,
* CollationStrength and DecompositionMode settings will return different
* CollationKeys for the same set of strings. Locales have specific
* collation rules, and the way in which secondary and tertiary differences
* are taken into account, for example, will result in different CollationKeys
* for same strings.
* <p>
* @see Collator
* @see RuleBasedCollator
* @version 1.3 12/18/96
* @author Helena Shih
* @stable ICU 2.0
*/
class U_I18N_API CollationKey : public UObject {
public:
/**
* This creates an empty collation key based on the null string. An empty
* collation key contains no sorting information. When comparing two empty
* collation keys, the result is Collator::EQUAL. Comparing empty collation key
* with non-empty collation key is always Collator::LESS.
* @stable ICU 2.0
*/
CollationKey();
/**
* Creates a collation key based on the collation key values.
* @param values the collation key values
* @param count number of collation key values, including trailing nulls.
* @stable ICU 2.0
*/
CollationKey(const uint8_t* values,
int32_t count);
/**
* Copy constructor.
* @param other the object to be copied.
* @stable ICU 2.0
*/
CollationKey(const CollationKey& other);
/**
* Sort key destructor.
* @stable ICU 2.0
*/
virtual ~CollationKey();
/**
* Assignment operator
* @param other the object to be copied.
* @stable ICU 2.0
*/
const CollationKey& operator=(const CollationKey& other);
/**
* Compare if two collation keys are the same.
* @param source the collation key to compare to.
* @return Returns true if two collation keys are equal, false otherwise.
* @stable ICU 2.0
*/
bool operator==(const CollationKey& source) const;
/**
* Compare if two collation keys are not the same.
* @param source the collation key to compare to.
* @return Returns true if two collation keys are different, false otherwise.
* @stable ICU 2.0
*/
bool operator!=(const CollationKey& source) const;
/**
* Test to see if the key is in an invalid state. The key will be in an
* invalid state if it couldn't allocate memory for some operation.
* @return Returns true if the key is in an invalid, false otherwise.
* @stable ICU 2.0
*/
UBool isBogus() const;
/**
* Returns a pointer to the collation key values. The storage is owned
* by the collation key and the pointer will become invalid if the key
* is deleted.
* @param count the output parameter of number of collation key values,
* including any trailing nulls.
* @return a pointer to the collation key values.
* @stable ICU 2.0
*/
const uint8_t* getByteArray(int32_t& count) const;
#ifdef U_USE_COLLATION_KEY_DEPRECATES
/**
* Extracts the collation key values into a new array. The caller owns
* this storage and should free it.
* @param count the output parameter of number of collation key values,
* including any trailing nulls.
* @obsolete ICU 2.6. Use getByteArray instead since this API will be removed in that release.
*/
uint8_t* toByteArray(int32_t& count) const;
#endif
#ifndef U_HIDE_DEPRECATED_API
/**
* Convenience method which does a string(bit-wise) comparison of the
* two collation keys.
* @param target target collation key to be compared with
* @return Returns Collator::LESS if sourceKey < targetKey,
* Collator::GREATER if sourceKey > targetKey and Collator::EQUAL
* otherwise.
* @deprecated ICU 2.6 use the overload with error code
*/
Collator::EComparisonResult compareTo(const CollationKey& target) const;
#endif /* U_HIDE_DEPRECATED_API */
/**
* Convenience method which does a string(bit-wise) comparison of the
* two collation keys.
* @param target target collation key to be compared with
* @param status error code
* @return Returns UCOL_LESS if sourceKey < targetKey,
* UCOL_GREATER if sourceKey > targetKey and UCOL_EQUAL
* otherwise.
* @stable ICU 2.6
*/
UCollationResult compareTo(const CollationKey& target, UErrorCode &status) const;
/**
* Creates an integer that is unique to the collation key. NOTE: this
* is not the same as String.hashCode.
* <p>Example of use:
* <pre>
* . UErrorCode status = U_ZERO_ERROR;
* . Collator *myCollation = Collator::createInstance(Locale::US, status);
* . if (U_FAILURE(status)) return;
* . CollationKey key1, key2;
* . UErrorCode status1 = U_ZERO_ERROR, status2 = U_ZERO_ERROR;
* . myCollation->getCollationKey("abc", key1, status1);
* . if (U_FAILURE(status1)) { delete myCollation; return; }
* . myCollation->getCollationKey("ABC", key2, status2);
* . if (U_FAILURE(status2)) { delete myCollation; return; }
* . // key1.hashCode() != key2.hashCode()
* </pre>
* @return the hash value based on the string's collation order.
* @see UnicodeString#hashCode
* @stable ICU 2.0
*/
int32_t hashCode() const;
/**
* ICU "poor man's RTTI", returns a UClassID for the actual class.
* @stable ICU 2.2
*/
virtual UClassID getDynamicClassID() const override;
/**
* ICU "poor man's RTTI", returns a UClassID for this class.
* @stable ICU 2.2
*/
static UClassID U_EXPORT2 getStaticClassID();
private:
/**
* Replaces the current bytes buffer with a new one of newCapacity
* and copies length bytes from the old buffer to the new one.
* @return the new buffer, or nullptr if the allocation failed
*/
uint8_t *reallocate(int32_t newCapacity, int32_t length);
/**
* Set a new length for a new sort key in the existing fBytes.
*/
void setLength(int32_t newLength);
uint8_t *getBytes() {
return (fFlagAndLength >= 0) ? fUnion.fStackBuffer : fUnion.fFields.fBytes;
}
const uint8_t *getBytes() const {
return (fFlagAndLength >= 0) ? fUnion.fStackBuffer : fUnion.fFields.fBytes;
}
int32_t getCapacity() const {
return (fFlagAndLength >= 0) ? (int32_t)sizeof(fUnion) : fUnion.fFields.fCapacity;
}
int32_t getLength() const { return fFlagAndLength & 0x7fffffff; }
/**
* Set the CollationKey to a "bogus" or invalid state
* @return this CollationKey
*/
CollationKey& setToBogus();
/**
* Resets this CollationKey to an empty state
* @return this CollationKey
*/
CollationKey& reset();
/**
* Allow private access to RuleBasedCollator
*/
friend class RuleBasedCollator;
friend class CollationKeyByteSink;
// Class fields. sizeof(CollationKey) is intended to be 48 bytes
// on a machine with 64-bit pointers.
// We use a union to maximize the size of the internal buffer,
// similar to UnicodeString but not as tight and complex.
// (implicit) *vtable;
/**
* Sort key length and flag.
* Bit 31 is set if the buffer is heap-allocated.
* Bits 30..0 contain the sort key length.
*/
int32_t fFlagAndLength;
/**
* Unique hash value of this CollationKey.
* Special value 2 if the key is bogus.
*/
mutable int32_t fHashCode;
/**
* fUnion provides 32 bytes for the internal buffer or for
* pointer+capacity.
*/
union StackBufferOrFields {
/** fStackBuffer is used iff fFlagAndLength>=0, else fFields is used */
uint8_t fStackBuffer[32];
struct {
uint8_t *fBytes;
int32_t fCapacity;
} fFields;
} fUnion;
};
inline bool
CollationKey::operator!=(const CollationKey& other) const
{
return !(*this == other);
}
inline UBool
CollationKey::isBogus() const
{
return fHashCode == 2; // kBogusHashCode
}
inline const uint8_t*
CollationKey::getByteArray(int32_t &count) const
{
count = getLength();
return getBytes();
}
U_NAMESPACE_END
#endif /* #if !UCONFIG_NO_COLLATION */
#endif /* U_SHOW_CPLUSPLUS_API */
#endif
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